Telephone system



Feb. 12, 1935. w. w. CARPENTER ET AL 1,991,193

I TELEPHONE SYSTEM Filed Oct. 12, 1933 W n! CARPENTER nvve/vroes E. H CLARK Patented Feb. 12, 1935 T D- T TE Louisa PA OFFICE This invention relates to a telephone system andparticularly to a'small capacity automatic telephone system. I I l An object of the invention is to provide im-' proved and economically arranged system's :ior

automatically establishing connections between telephone lines through a single ing. unit.

Heretofore systems have. been providedt for establishing connections between two subscribers lines in .a single cross-bar switching unit by means of links having line finders and selector branches for connecting the two 1 lines at two cross-points of the switch.- The arrangement is such that a calling line :is:' automatically connectedto'the line finder branch of an idle link of January 18, .1916, to J. N. Reynoldsmay be in response to the seizure of theiline and'the called line. is connected. to the selector'branch of the; idle link in "response to dial pulsesincoming over the calling subscribers line-p ,Thetdial desired magnet that connects the called subscribers line to the selector branch. Asystem" of .this

kind is disclosed in the patent tO'L-R,W8,11EI' 1,567,309 of December 29, 11925.1:

A feature of this invention is anarrangement in a systemof this kind; whereby the linerelay of the calling subscribers line isused as alockbut means to prevent any other line 'from' initiating a call while a connection isbeing'estab lished to a called line" throughrthe i cross-bar switch, whereby said line. relay causes 'the direct operation of the line magnet in. the switch which identifies the calling line for a :connectionto the said line relay also cause'sthe'idle link. to be chosen and the magnet .of theline finder branch to be actuated to establish a connection between this branch and the calling line.

Another feature of thisinvention is an arrangement whereby the line-magnet. identifying the desired called line for a connection at a cross-point to the selector branch of: a chosen link is selected throughia circuit, so arranged that each operation of a pulsing relay in the line finder branch which operates in response toimpulses incoming over the calling line, actuates a succeeding line magnet and releases'ajipreceding line magnet until the magnet of the called line l is reached. latter line'magnet temporarily locks and the magnet of the selector branch of the chosen link is thereuponautomatically.actu ated to connect this branch to 'the called line, whereupon the called line magnet is released.

cross-bar switcha switchhook toconnect his line with the line finder branch oflan idle link within a certain period thereafter, the establishing of a connec:

tionjto the called lihe over the selector branch of the link is prevented and whereby under such circumstances this link is released fromthe calling line and "the calling line is then connected to a holding'trunk in the switch.

r This invention has been illustrated a the ac- Tcompanying drawing which shows one embodiment oifethe invention An ordinary cross-bar switch of the type disclosed in Patent 1,168,419

employed and hasbeen illustrated in diagrammatic term at S. This switch may be arranged. 'i'oranumber of linesl to O terminating in the switch at cross-points; in contact sets arranged in'a horizontal rowfor each line. Of these lines 1]; ,2, 9 andio only have been shown. The con- 1 tact sets of these lines have access at the various cross-pointsto contact sets associated with links we of which have been shown'atll and B respectively. The calling lines have access to the l branch A1 "of link A or B1 of linkjB and the called lines have access to the branch A2 of link A or B2'of lijnk'B... A holdingftrunk c has .major portion of the circuits individual to link.

line finder branch of an idle ,link, and whereby B has been omitted but may terminate at .E. 1

The circuitiequipment common to both links has beenshownat F. The horizontal operating mag nets forconnecting the lines to the linkshave been shown as follows: the magnet for line l at S1, for line'2' at S2, for line 9 at S9, and

for lineO atSO. The vertical operating magnets branch B2, while the verticaloperatingtmagnet for the holding trunk C hasbeen shown at 14.

It should'bedunderstood thatrthe operation'of one horizontal magnet followed by-the operation of one vertical magnet and the. release ,of the Loperated horizontal magnet causes a" connection to be established between a line and a branch "of an idle link or between a line and the holding trunk C in the same manner as outlined in'the above mentioned patent to Reynolds.

A description will nowbe made of the opera- 30 also been shown'to which each line has access tion of these circuits .whileestablishing a connection from a' calling line 1 to a called line 2, over the link A. r If the subscriber of line 1 lifts his receiver from the switchhook a connection is established through the subscribers loop in the usual manner from groundat contacts of relay 20, over the ring conductor through the loop a backover the tip conductor, contacts of relay through a Winding of relay 21, contacts of relay 22 to battery. This causes the operation of relay 21.

corresponding to relay 21 of the other lines, Winding of relay 22 to ground at'c'ontac-t's of relay 23; The operation of relays 21 and. 22 closes acircui-t for the, operation of the magnet S1 and relay 24 from battery-through the Windingpf this magnet,

'contactseof I relay :21; contacts of relay 22, windingofrelay 24', togroundatcontacts' of relay 25. Relay 2221150010863,& Cil'Cl1llljfOI;th6 timing relay 26' from batterythrough the, windingoffthis re-.

lay, contacts of relay 22'to ground, This circuit also branches out through a thermostatic device 27 associated with the relay 26.' to re-establish theconnection between the armature 1 and. back .contact' of relay 26 after a certain interval, The

purpose of -relay. 26 and its thermostatic device is to disconnect :the calling-Qlinefrorn the seized branch of an idle link-a certain-interval after the calling subscriberhhas removed his receiver irom the switchhook ifhe 'has taken no further action v towards. the establishingof a connection 1 to a desired line through-, the'seized link, A de pends on whether relay 29 is operated orin normal condition. The operation of-relay 24. closes a circuit for the operationofrelay23hr the'link Alas irel'ay 29 is not actuated This "circuitmay be traced ,from battery at contacts of relay 124,

7 contacts of relay '32,- windingfof'relay'28 to ground atcontacts ofrelay 29. j It'the'llink B had-"been idle relay 3Q would have been operatedqfThis rela'y inpperating would have open'edjthe hold;

*inggpath for relay 28 through its armature' and I backcontact ajs well "as its original' energizing circuit due the subsequent operation of relay 32,"thus preventing relay 28 from being main tained operating. However; as branch A is idle relay28 is operated and closes an obvious circuit for theoperation of relay 3:1. Relay 28 now closes a locking circuit for itself and forthe operationofrelay 32 f rozn battery, the other Winding'ofrelay28 fand an armature and front contac't, an armature and back contact of relay 30,

. winding' of rela'y 32; to E round'at 'the'contactsof relay23} Pielay 31 is also operated by'the operation ofirelay28 from battery, winding of relay- 34,

an a-rii iatur'e and back contact ofrelay 35, an armature' and front contact of: relay 28 to ground at make before break contactsof 'relay'36; The purpose of the operationof relay: '34 will become apparenthereinafter; The operation of re.-

lay-32 closesza circuit fortheqoperation ofithe magnet lflfor connecting the branch A1 of link A to the calling line 1. The circuits for this magnet may be'traced from battery, winding of mag net 10, ran armature and front contact of relay 31 This relay operating closes a locking circuit for itself and a circuit for the operation of relay 22 as follows: From battery throughthe'otherwinding. of relay 21, an armature andfront contact of 'this relay, armatures and back contacts of relays an armature and back contact of relay and an armature and front contact of relay 32 to ground at contacts of relay 23. The. calling subscribers through the windings of pulsing, relay 39,. This relayfin operating closes an obvious circuit-for relay 40 which in turn closes anobvious circuit for relay 29. Relay 29 in operating closes a circuit for the operation of relay 20 from battery, winding' of relay 20, the sleeve conductor and contacts at 41 of the cross-bar switch, contacts of relay 291to ground aticontacts of relay 43; Relay 29 in operating'also closes an obvious locking ci'r-.

magnet S1 and relay 24 causingthern to release and opens the original energizing circuit for magnet -10.which is held'operated by the locking circult *over the sleeve conductor. A .di'al toneci's now transmitted to. the calling. subscribers telephone set from the dial tone source at ea'an armature and front contact of relay 31,-condenser Eon thefirst'impulse cause the release and reoperationcf the pulsing relay 39; a On the -release of. relay'x39 a circuitis'completed for the operation ofgrelay 36-f-rom'battery, winding of this. relay, an armature and back contact of 1 relay 39 to ground Relay'Bdinioperatizig opens the circuit for relay,

34 thus permitting relay 35 to operate from ground :atcontactssof'relay 32- 'which now hold bothreiays134 I'and'35 operated. A circuit is also com; pleted' d-ueto the release of relay 39.1fm the eberation of 're1ay'46. This circuit may-be traced from battery-throughza resistance and winding of relay. 46, 'make before-break contacts 'of-relay 46., an armature and front .conta'ctcf relay'JF-l, an armature and .front contact of relay: 29 'to ground at annarmature and back contactofnel-ay 39i .Wheninow the. pulsing relay 3911's again ope erated at the end of the first impulse,;a 'circu-itis completed for the operation of relay 5G. This circuit may be "traced from battery through :a resistance, winding-of relay 50, an armature and front contact 'of relay 46 to ground atthe contacts of relay"23.f It should be'noted now that "role *a 46 ancluSO are locked to this ground at relay23. Trie 'operation'ofrelay 50 closesa circuit for mage net S1 from battery winding of this magnet,-- an armature and. front contact of relay. 50,. make- -beiore-break contacts of magnet S1 corre sponding make-before-break contactsof Lthe s'uc :cee'ding horizontal .ma'gnets an Larinature land front contact of relay 25,: an armature and-front leased at the beginning of thesecond; impulse;

' at 'an armature and front contact of ""relay 29.,

ing circuit therefor.

short circuit is provided for the release ofrelay 46 by the ground from an armatureand back contact of relay 39 and an armature and front contact of relay 50. When relay,46 is releasedthe relay 50 remains operated through the makebefore-break contacts of relay 46 to the ground at relay 39. i The magnet S2 is now operated from battery throughthe winding of this magnet, an armaturev and front contact of: magnet 81 an armature and back contact of relay 46 toground. Magnet S2 provides a locking circuit foritself through one of its armatures and front contact to, the ground at relay 35, and opens the holding circuit for magnet S1 which is thereby-J re,- leased. When the pulsing re1ay 39 is againgoperated, the ground is removed fromthe holding circuit for relay 50 which is thereby released. If

succeeding magnet S3,(not shown) would, have been operated,.while if a fourth impulsehad been received, the relays 46 and 50 would have been released 'and the fourth magnet would have been operated. That is, the relays 46 and50are there- ;fore alternatively operated and released ,by the succeeding impulses.

It should also be noted that at eachoperation of a succeeding S magnet the immediate preceding S magnet releases dueto opening of the locks vAs only two impulses are transmitted in'this case to select line 2, thefinal operation of the pulsing relay 39 causes the: re-

leaseof relay 36. Relay 36 in releasing causes operation of relay 53 and magnet 11 from battery,

V winding of magnet 11, an armature and front con:-

tact of relay 31, an armature, and back contact of relay 54, winding ofrelay 53 toground at the armature and front contact of relay 52. The operation ofmagnet 11, establishes-a connection from the branch A2 of link A through the contacts at 56 to the tip andringconductors' of; line 2.

The contacts at 56 now also closea circuitfor the operation of relays.5'7 and 58 from battery,"

winding of relay 58, sleeve contacts at*56;a,wind

ing of relay 57, an armatureand 'frontcontact of relay 48 to ground. 'Relay57 in operating provides a locking circuit for itself .and relay 58 through an armature and front contacts to ground at relay 29 independent of the ground at relay,48

which relay will presently release. ,Rela'y 58111.01): I

crating disconnects theline 2 from relay 59 to prevent this latter relay :from operating when the called subscriber answers. Magnetll-Lis locked through its armature and front contact',contacts at 41,, an armature and front contact, of relay. 29 toground at an armature and back contact of re: lay 43. Relay 53 in operating closes an obvious circuit for the operation of relay 60but as relay 53 immediately thereafter, releases due to the short-circuiting ground from relay 29sthat holds magnet 11 operated the operation of re1ay60 may then close a circuit for the operation of relay 23 from battery winding of relay 60, armature and front contact of relay 60, winding of relay 2 3. to

ground at an armature and front contact ofrelay 32. The operationof relay 23 causes the ;re-

, leasegoftheyrelaysand magnet S2 held operated wouldnowjbe, released, but'due 5130 the fact that only two .impulses were transmitted they have already been released. For example, 'ifthree im-' pulses have been, transmitted they would have been operated'at this time and would now-release. Relaysreleasing at this time are 32, 28, 31, 35, 34,

25, 52,21, 22, 26, andrelay 32 in releasing causes thereleaseloftrelays 23 and 60. a

\It should be noted that when relay 57 operated and before relay 48; released-1a circuit was completed for the operation of relay 62 from battery, windingof this relay, an armature and frontcontactof relay-57, anarmature and front contact of relay 4 8 to ground; Relay 62, immediately locks over an armature and front contact through an armature and back-contact of the ringing trip relay 63,, an armatureand frontcontact of relay29 to gground at relay, 43. At this time a therefore only" relays 57, 62, 39, 40, 29, 20' and. 58 remain operated. The operation of relay ,62

closes a circuit from; a ringing source at '65, the winding of ringing. relay {63,ana'rmature and front contact ofrelay 62, contacts at 56, the ring conductor through the, called subscribers telephone set and :backover the tipconductor, con-,

tacts at;56,an armature,and front contact of relay 62 to ground, to transmit ringing current to, call the subscriber of line 2. When the subrelay in turn opens jthe ringingcircuit and causes the operation of relay 66 from battery, winding of thisrelay,; an armature and back contact of relay 62, an armatureiand frontcontact of relay 5'! to ground at the armature and back contact of relay 4-8. The ringing relay 63 is then released. A, conversationalconnection is n'ow established from the calling subscriber on line lithrough the crossbarswitch contacts at 41, the branch A1 a of link-A, condensers 45 and 68, armatures'and front contacts of relays 66, cross-bar switch contacts at. 56,.tthe ,tip and ring-conductors, to the subscriber of, line Talking battery for, the calling line lis providedirom the source through thewindings ,of the pulsing relay 39, and talking battery 1.01? the called line" is provided .from the source through the windings of-relays 67; When the calling, subscriber releases, relays 39, 40 and 29 are released causingthe release, of relays 57, 66,20. and 58 jandthe vertical magnets 10 and 11. The circuits are thereby returned to normal I condition. I] a A" description will now be made of the opera tion of'jthesecircuits torelease the A seized r by thecalling subscribers line 1 whenthe calling subscriber removes the receiver fro'r'nqthe hook in case he does not dial within acertain period thereafter,- andihow thecalling subscribers line i is transferred to the holdingtrunk ,C j and prevented from again seizingan idle link until after he has replaced the receiver onthe switchhook.

It should be remembered that when the branch ALof. link A was seized relay26 was operated 'o'nnthe operationlof relay 22. :If the subscriber fails lto that within a certain period the, thermostatic element 27- will be sufliciently heated to move the armature of relay 26 to-close, its back contact When this takes place a circuit is completed ,for-theqoperation of relay 54 from battery, winding of this relay,-; armature and back and '60 and magnet S1;

I to, said branch-, and means for thereafter con i necting any one of the, other lines to the other 'branch of said link including the operation of the magnet of the theoperation of relay 43 "from'battery, winding of this relay, contacts of relay 31, contacts-circ lay 54 to ground at contacts'of relay'32. Relay as in operatingcauses-the'release of relay 25 and this relay in turn causes the op'erationof relay 24 and horizontal magnet 61'; Relay'24 causes the operationof theverticalmagnet 14am re lay'53 over a-circuit from battery, winding of magnet 14, contacts of relay 54; w-in'dingof relay 53, contacts of relay2eflcontacts of 'relayJ54, to

' ground at contacts ofrelay 32mRelay 53 'operates relay 60, magnet 14 closes the connection' for the calling line 1 through'contacts' at 71 0f the operating also opens the circuit for the magnet 10 thereby-causing the release 'o'f'thefcallin'g sub scribers linefrom the branch A1 of the link-A. This causesthereleaseof relays 39, 40 and 29. The'operation of relay 23 now causes the release of certain other relays remaining actuated at this time such as 32, 28, 31, 34, 22, 24, 21, 26, 54, 23 The calling subscriber of linel is now thereforeconnected to trunk C and prevented from seizing an idle link to extend a connection through the switch and until after he has replaced the receiver on the switchhook when relay 72 is released causing therelease of relay 20 and magnet 14. Hemaythenagain remove the receiver to initiate a call in'the usual manner as heretoforedescribedQ What is claimed is: i

1. In a telephonefsystempa cross-bar'switch,

Zines terminating in said switch, links having two branches terminating in said switch, a line relay for eachline operative on the seizure of a line by a calling subscriber, a line magnet for each line, a magnet for each branch; means responsive to the actuation-of the line relay of a calling line for preventing the operation of any otherrline relay in case any other subscriber seizes his line, means responsive to the actuation of said line relay for directly operating the associated line magnet, means responsive'tofl the actuation of saidline relay for selecting an idle link and for actuating'the magnet for one branch of said-link to connect the calling line the line magnet of the otherline connected and other branch connected to the calling line; 7

'2. In a telephone syst'em, a cross-bar switch, lines terminating in said switch,'links having] two branchesterminating in said switch, a line relay for each line operativeion the seizure of a line by a callin'gsubscriber, a line magnet for each line; amagnet for each branch, means responsive to the actuation of the line relay of a callinglline for preventing the operation of 'any'other line relay in case any other subscriber seizesihis line, means responsive to the actuation ofsaid line relay for directly operating the associated line mag- ,net, means responsive to the actuation of said line relay for selecting an idle link and for actuating the magnet for one branch of said link to connect the calling line to'said branch, at pulsing relay in said branch,I-means responsive'to the connection; ofsaid branch to the calling line for *actuatmgsaid-pulsing relay, means responsive to the actuation of said pulsing" relay for releas ingthe calling line magnet and for holding said actuated branch magnet operated;

-3. In a telephone systein, across-bar switch, lines terminating in said switch, links having two branches terminating in'jsaid switch, a line relay for each line operative on the seizure of a; line by its calling 'subscribena line magnet foreach "line; a'miagne't for each branch, means responsive to the actuation of a line relay for preventingthe operation of any other 'line relayin case any other subscriber seizes his'lin'e 4. In a telephone system, a cross-bar switch,

trolled 'over said connectedflbranch for actuating and releasinglin succession the line magnets until ofisaid link to said called line'including the ternporary" maintaining of the line magnet of the c'alled-lineioperated and the permanent operation ofthe magnet of said other branch, and means thereafter operatedifor inductively connecting said branches together. 9 K 5: In a telephone'system, across-bar switch, lines terminating'in'said switch, links terminating insaid switch,means for establishinga connection from any calling line to: any other line through an:idl'e link responsiveto' two separate succeeding actions on the part of the calling subscriber, and means :operativei'to prevent a connection from beingestablished if the second action is not taken within a certain interval after the first action.

Ina-telephone system, a cross-barswitch, 7

lines terminating in said switch, links terminating in'saidswitch, means responsive to "the subscriber of -aca'lling line removinghis receiver from the switchhookl for connecting his' 'line to an idle link,

means responsive to impulses received over the calling 'lin'e' for connecting said idle link-to any ,other'valine," means'ifor releasingthe calling line from said idle link'a certain period after the removal of the-receiver from the switchhook if e insaid-switch, meansforiseizing an idle. link from any *calling line,'means-for connecting any other lineto-saidseized link,- means for releasing the seized link from a calling line if no action is taken towards the establishing of a connection to any '25 the line'magnet of a desired called line is reached, 'means for thereafter connectingithe other branch other'line'within a certain period after the seizure of the link, and means for thereafter preventing the reseizure of an idle link by said calling line as long as the' calling 'subscribers receiver remains off th'ehook; V V

v 8'. In a telephonev system, across-bar switch,

lines terminating in said switch, links terminat ing in-said switch, means for establishing a con ne'ction'irom any Callillgjllnjto any other line ti'on frombeing completed if impulses are not received within a certain period after the removal of the receiver from the switchhook. 1

9. In a telephone system, a cross-bar switch,

lines terminating in said switch, links terminating in said switch, means for establishing a con- 1 nectiorr from any calling line to any other line over an idle link operative by the calling subscriber removing his receiver from the switch hook followed by impulses transmitted over the calling line, a special link terminating insaid switch, means operativeto prevent said connection from being completed if impulses are not received within a certain period after the receiver is removed from the switchhook, and means thereafter operative for connecting thecalling line to said special link and maintaining this connectionuntil the calling subscriber replaces his re-,

ceiver on the switchhook.

10. In a telephone system, a cross-bar switch, lines terminating in said switch, links terminating in said switch, means for establishing a connection from any calling line to any other line over I an idle link operative by the calling subscriber removing his receiver from the switchhook followed by impulses transmitted over the calling line, a special link terminating in said switch, means for releasing the calling line from said idle linka certain-period after the removal of the re ceiver if impulses are not received within thisperiod, means thereafter operative for connecting the calling line to said special link, and means for disconnecting the calling line from said special link when the calling subscriber replaces his receiver on the switchhook. l

11. In a telephone system, a cross-bar switch, 1 lines terminating in said switch and arranged in rows, links terminating in said switch having two branches and arranged in rows intersecting the line rows, line connecting magnets one for each line, link connecting magnets one for each branch,

a. pulsing relay meansalssociated with one branch of each link, means responsive tothe seizure of a calling line for selecting an idle link for connecting the calling line with the branch of said idle sive' to the actuation of the pulsing relay means of theconnected branch by impulses received over 1 the calling line for actuating and releasing in suc cession the line connecting magnets until the magnet of the desired line is actuated and for thereafter actuating the connecting magnet 0f the other branch of the seized link to connect said branch with the called line at the intersecting point of the corresponding rows of said called line and. said other branch, means thereafter.

operative for signaling the subscribers of said I called line, and means operatively responsive to the called subscriber answering thefcall for, connecting the two branches of the seized link together to establish a conversational connection between the calling and the called subscribers lines. 7

12. In a telephone systema cross-bar switch, lines terminating in said switch, links having two branches terminating in said switch, a line relay for each line operated on the seizure of, a line by its calling subscriber, a line' magnet for each line, a magnet for each branch, a relay,

means for operating said relay in response to the 1 operation of any one of said line relays, and,

means responsive to the operation of said relay for preventing the operation of any other line relay in case anyv other subscriber seizes his line;

ARREN W. CARPENTER.

EDGAR H. CLARK. 

